From: Greg Aldering (aldering@panisse.lbl.gov)
Date: Thu May 01 2003 - 10:41:15 PDT
Hi Rob,
*IF* you want to add the 2dFGRS power spectrum constraints to our OM,w
fits, here is how. Note that we already have included the 2dFGRS galaxy
redshift distortion constraints, which are less model dependent but also
less constraining.
Basically, the 2dFGRS power spectrum fits give OM*h = 0.20 +/- 0.03
*after* including a prior of h = 0.7 +/0.07 (see Percival ref, below).
For reference, the HST Key Project quotes h = 0.72 +/- 0.08. Using
h = 0.72 as the central value, and assuming that 2dFGRS errors simply
puff-up by 0.08/0.07 in going from h = 0.7 +/0.07 to h = 0.72 +/- 0.08,
one gets OM = 0.278 +/- 0.048. Since this is based on fitting power
spectra, it should not need to be corrected to z = 0, in which case,
there is no w dependence.
Note that WMAP also constrains h, which is ignored in this analysis.
However, I think that our SN data already cut away the WMAP data in
the range where it adds useful constraints on h relative to the
HST Key project. Note also that WMAP and HST get the same h.
My first concern with this measurement is that it is based on an early
version of 2dFGRS. The Hawkins redshift distortion analysis uses the
much larger completed survey, but then trims the volume to get a
better-defined sample. The redshift space distortion measurement for
the Percival-era 2dFGRS was higher than the Hawkins value. So, when
they do a new power spectrum analysis, that value might come down too.
Also, unlike the CMB spectrum, the galaxy power spectrum has a lot more
physics that has to be assumed to get a relation to the cosmological
parameters. However, it is a popular source to quote, and I am
pretty sure that this measurement is largely independent of the Hawkins
measurement (if nothing else, only 2/3 of the galaxies are the same.)
- Greg
P.S.
The reference is:
ARTICLE{2001MNRAS.327.1297P,
author = {{Percival}, W.~J. and {Baugh}, C.~M. and {Bland-Hawthorn}, J. and
{Bridges}, T. and {Cannon}, R. and {Cole}, S. and {Colless}, M. and
{Collins}, C. and {Couch}, W. and {Dalton}, G. and {De Propris}, R. and
{Driver}, S.~P. and {Efstathiou}, G. and {Ellis}, R.~S. and
{Frenk}, C.~S. and {Glazebrook}, K. and {Jackson}, C. and {Lahav}, O. and
{Lewis}, I. and {Lumsden}, S. and {Maddox}, S. and {Moody}, S. and
{Norberg}, P. and {Peacock}, J.~A. and {Peterson}, B.~A. and
{Sutherland}, W. and {Taylor}, K.},
title = "{The 2dF Galaxy Redshift Survey: the power spectrum and the matter content of the Universe}",
journal = {\mnras},
year = 2001,
month = nov,
volume = 327,
pages = {1297-1306},
adsurl = {http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2001MNRAS.327.1297P&db_key=AST},
adsnote = {Provided by the NASA Astrophysics Data System}
}
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